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drm/i915: check that rpm ref is held when accessing ringbuf in stolen mem

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While running some tests on the scheduler patches with rpm enabled I
came across a corruption in the ringbuffer, which was root-caused to
the GPU being suspended while commands were being emitted to the
ringbuffer. The access to memory was failing because the GPU needs to
be awake when accessing stolen memory (where my ringbuffer was located).
Since we have this constraint it looks like a sensible idea to check
that we hold a refcount when we access the rungbuffer.

v2: move the check from ring_begin to ringbuffer iomap time (Chris)
v3: update comment (Chris)

Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1453909429-11024-1-git-send-email-daniele.ceraolospurio@intel.com
This commit is contained in:
Daniele Ceraolo Spurio 2016-01-27 15:43:49 +00:00 committed by Daniel Vetter
parent 2417c8c03f
commit ff3dc0875c
1 changed files with 3 additions and 0 deletions
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3
drivers/gpu/drm/i915/intel_ringbuffer.c
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@ -2119,6 +2119,9 @@ int intel_pin_and_map_ringbuffer_obj(struct drm_device *dev,
return ret;
}
/* Access through the GTT requires the device to be awake. */
assert_rpm_wakelock_held(dev_priv);
ringbuf->virtual_start = ioremap_wc(dev_priv->gtt.mappable_base +
i915_gem_obj_ggtt_offset(obj), ringbuf->size);
if (ringbuf->virtual_start == NULL) {